From: "Van Haaren, Harry" <harry.van.haaren@intel.com>
To: "Ye, Xiaolong" <xiaolong.ye@intel.com>, Itsuro Oda <oda@valinux.co.jp>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
"maxime.coquelin@redhat.com" <maxime.coquelin@redhat.com>,
"Wang, Zhihong" <zhihong.wang@intel.com>,
"stable@dpdk.org" <stable@dpdk.org>
Subject: Re: [dpdk-stable] [dpdk-dev] [PATCH] vhost: make iotlb cache name unique among multi processes
Date: Tue, 10 Mar 2020 12:44:24 +0000 [thread overview]
Message-ID: <MWHPR1101MB215772487292E1D005542FFAD7FF0@MWHPR1101MB2157.namprd11.prod.outlook.com> (raw)
In-Reply-To: <20200310113206.GA14733@intel.com>
> -----Original Message-----
> From: dev <dev-bounces@dpdk.org> On Behalf Of Ye Xiaolong
> Sent: Tuesday, March 10, 2020 11:32 AM
> To: Itsuro Oda <oda@valinux.co.jp>
> Cc: dev@dpdk.org; maxime.coquelin@redhat.com; Wang, Zhihong
> <zhihong.wang@intel.com>; stable@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH] vhost: make iotlb cache name unique among
> multi processes
>
> On 03/10, Itsuro Oda wrote:
> >Currently, iotlb cache name is comprised of vid and virtqueue
> >index. For example, "iotlb_cache_0_0". Because vid is assigned
> >per process, iotlb cache name is not unique among multi processes.
> >For example a secondary process uses a vhost
> >(ex. eth_vhost0,iface=/tmp/sock0) and another secondary process
> >uses a vhost (ex. eth_vhost1,iface=/tmp/sock1), iotlb cache
> >name of both vhost ("iotlb_cache_0_0") are same and as a result
> >iotlb cache is broken.
> >
> >This patch makes iotlb cache name unique among milti processes
> >by using the interface name not vid to comprise iotlb cache name.
> >Since the length of interface name is variable, this patch uses
> >hash value calculated by the interface name.
> >
> >Fixes: d012d1f293f4 (vhost: add IOTLB helper functions)
> >Cc: stable@dpdk.org
> >
> >Signed-off-by: Itsuro Oda <oda@valinux.co.jp>
> >---
> > lib/librte_vhost/iotlb.c | 8 ++++++--
> > 1 file changed, 6 insertions(+), 2 deletions(-)
> >
> >diff --git a/lib/librte_vhost/iotlb.c b/lib/librte_vhost/iotlb.c
> >index bc1758528..0992c145b 100644
> >--- a/lib/librte_vhost/iotlb.c
> >+++ b/lib/librte_vhost/iotlb.c
> >@@ -6,6 +6,7 @@
> > #include <numaif.h>
> > #endif
> >
> >+#include <rte_jhash.h>
> > #include <rte_tailq.h>
> >
> > #include "iotlb.h"
> >@@ -288,6 +289,7 @@ vhost_user_iotlb_init(struct virtio_net *dev, int
> vq_index)
> > char pool_name[RTE_MEMPOOL_NAMESIZE];
> > struct vhost_virtqueue *vq = dev->virtqueue[vq_index];
> > int socket = 0;
> >+ uint32_t val;
> >
> > if (vq->iotlb_pool) {
> > /*
> >@@ -308,8 +310,10 @@ vhost_user_iotlb_init(struct virtio_net *dev, int
> vq_index)
> > TAILQ_INIT(&vq->iotlb_list);
> > TAILQ_INIT(&vq->iotlb_pending_list);
> >
> >- snprintf(pool_name, sizeof(pool_name), "iotlb_cache_%d_%d",
> >- dev->vid, vq_index);
> >+ val = rte_jhash(dev->ifname, strlen(dev->ifname), 0);
> >+ snprintf(pool_name, sizeof(pool_name), "iotlb_cache_%08x_%d",
> >+ val, vq_index);
> >+ VHOST_LOG_CONFIG(DEBUG, "IOTLB cache name: %s\n", pool_name);
Although very unlikely, what would happen if there is a hash-collision?
For example imagine two different names hash to the same "val", from
my understanding they will now use the same IOTLB but should not share one.
<snip>
next prev parent reply other threads:[~2020-03-10 12:44 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-10 5:00 [dpdk-stable] " Itsuro Oda
2020-03-10 11:32 ` Ye Xiaolong
2020-03-10 12:44 ` Van Haaren, Harry [this message]
2020-03-10 12:58 ` [dpdk-stable] [dpdk-dev] " Maxime Coquelin
2020-03-11 0:24 ` [dpdk-stable] [PATCH v2] " Itsuro Oda
2020-03-11 23:19 ` [dpdk-stable] [PATCH v3] " Itsuro Oda
2020-04-09 14:25 ` Maxime Coquelin
2020-04-10 14:45 ` Maxime Coquelin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=MWHPR1101MB215772487292E1D005542FFAD7FF0@MWHPR1101MB2157.namprd11.prod.outlook.com \
--to=harry.van.haaren@intel.com \
--cc=dev@dpdk.org \
--cc=maxime.coquelin@redhat.com \
--cc=oda@valinux.co.jp \
--cc=stable@dpdk.org \
--cc=xiaolong.ye@intel.com \
--cc=zhihong.wang@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).